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diff --git a/src/corelib/doc/snippets/qtracer/ftracer.cpp b/src/corelib/doc/snippets/qtracer/ftracer.cpp
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+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <QCoreApplication>
+#include <QLoggingCategory>
+
+
+//![1]
+QLoggingCategory theFooArea("foo");
+QLoggingCategory theBarArea("bar");
+QLoggingCategory theBazArea("baz");
+//![1]
+
+// Note: These locations are Ubuntu specific.
+
+// Note: To make the example work with user permissions, make sure
+// the files are user-writable and the path leading there accessible.
+
+const char traceSwitch[] = "/sys/kernel/debug/tracing/tracing_on";
+const char traceSink[] = "/sys/kernel/debug/tracing/trace_marker";
+
+// The base class only serves as a facility to share code
+// between the "single line" data logging aspect and the
+// scoped "measuring" aspect.
+
+// Both aspects and the base class could be combined into
+// a single tracer serving both purposes, but are split
+// here for clarity.
+
+// Error handling is left as an exercise.
+
+//![2]
+class MyTracerBase : public QTracer
+{
+public:
+    MyTracerBase() {
+        enable = ::open(traceSwitch, O_WRONLY);
+        marker = ::open(traceSink, O_WRONLY);
+    }
+
+    ~MyTracerBase() {
+        ::close(enable);
+        ::close(marker);
+    }
+
+protected:
+    int enable;
+    int marker;
+};
+//![2]
+
+
+//![2]
+class MyTracer : public MyTracerBase
+{
+public:
+    void start() { ::write(marker, "B", 1); }
+    void end() { ::write(marker, "E", 1); }
+};
+//![2]
+
+
+//![3]
+class MyDataLogger : public MyTracerBase
+{
+public:
+    MyDataLogger() {
+        buf[0] = 0;
+        pos = 0;
+    }
+
+    void record(int i) { pos += sprintf(buf + pos, "%d", i); }
+    void record(const char *msg) { pos += sprintf(buf + pos, "%s", msg); }
+    void end() { ::write(marker, buf, pos); pos = 0; }
+
+private:
+    char buf[100];
+    int pos;
+};
+//![3]
+
+// Simplest possible example for "measuring".
+//![4]
+int foo(int i)
+{
+    qCTraceGuard(theFooArea);
+    // Here could be some lengthy code.
+    return i * i;
+}
+//![4]
+
+// We can switch on/off tracing dynamically.
+// The tracer will be temporarily switched off at the third call
+// and re-enabled at the eighth.
+//![5]
+int bar(int i)
+{
+    static int n = 0;
+    ++n;
+    if (n == 3)
+        theBarArea.setEnabled(QtTraceMsg, false);
+    if (n == 8)
+        theBarArea.setEnabled(QtTraceMsg, true);
+
+    qCTraceGuard(theBarArea);
+    return i * i;
+}
+//![5]
+
+// An example to create "complex" log messages.
+//![6]
+int baz(int i)
+{
+    qCTrace(theBazArea) << 32 << "some stuff";
+
+    return i * i;
+}
+//![6]
+
+
+
+//![7]
+namespace {
+static struct Init
+{
+    Init() {
+        tracer.addToCategory(theFooArea);
+        tracer.addToCategory(theBarArea);
+        logger.addToCategory(theBazArea);
+    }
+
+    MyTracer tracer;
+    MyDataLogger logger;
+
+} initializer;
+}
+//![7]